Strong mechanical squeezing in a standard optomechanical system by pump modulation

We propose a simple yet surprisingly effective mechanical squeezing scheme in a standard optomechanical system that is beneficial for the amplitude modulation of the pump laser. By merely introducing a specific kind of periodic modulation into the single-tone driving field to cool down the mechanical Bogoliubov mode, strong mechanical squeezing, far beyond 3 dB, can be engineered without the requirement for any additional techniques. Specifically, we find that the amount of squeezing is not simply dependent on the order of magnitude of the effective optomechanical coupling but strongly on the ratio of sideband strengths for it. To maximize the mechanical squeezing, we numerically and analytically optimize this ratio in the steady-state regime, respectively. The mechanical squeezing engineered in our scheme also is extremely robust and can survive at a high bath temperature. Compared with previous schemes based on the two-tone pump technique, our scheme involves fewer external control laser sources and can be extended to other quantum systems to achieve a strong squeezing effect.